<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>我的第一个网页</title>
    <style>
        div{
            margin: 0 auto;
        }
        p{
            font-size: 2em;
            color: aqua;
        }
    </style>
</head>
<body>
    <div>
        <span>
            <p>Hello World!</p>
        </span>
    </div>
</body>
</html>